互感器的主要作用有：

The main function of instrument transformer is:

（1）将高电压变为低电压（100V），大电流变为小电流（5A，1A）。

(1) change the high voltage to low voltage (100V), and the high current to small current (5A, 1A).

（2）使测量二次回路与一次回路高电压和大电流实施电气隔离，以保证测量工作人员和仪表设备的安全。

(2) make the measurement of the two circuit and the primary circuit high voltage and high current isolation, so as to ensure the safety of measuring personnel and instrument and equipment.

（3）采用互感器后可使仪表制造标准化，而不用按被测量电压高低和电流大小来设计仪表。

(3) the instrument can be standardized after the instrument is used, but the instrument is not designed according to the magnitude of the measured voltage and the magnitude of the current.

（4）取出零序电流、电压分量供反应接地故障的继电保护装置使用。

(4) take out the zero sequence current and voltage component for the relay protection of the grounding fault.